The invention relates to a drilling device for producing drill holes having an undercut and comprising a drilling tool to be inserted into a drilling machine. The drilling tool includes a drilling shaft and a drilling head with driven plates located at the free end of the drilling shaft.
Drilling devices for producing drill holes that are provided in the region of the bottom of the drill hole with an undercut are known. The undercut is produced due to pivotal movement of the drilling shaft having a widened drilling head at the free end thereof. Into such a drill hole, there may be inserted an expansible fixing plug which, when in expansion, engages the undercut with a form-locking fit.
German Offenlegungschrift No. 33 40 090 discloses a drilling device for producing a drill hole with an undercut. Because of the pivotal movements carried out during the drilling operation for producing undercuts, the mouth of the drill hole often becomes damaged, and the drilling device, which is guided with a relatively large degree of play in a guide sleeve, frequently becomes jammed.